This invention relates to a method and apparatus for authenticating printed documents.
It is frequently required to provide some way of checking the authenticity of printed documents, to confirm that the document has been issued from a particular source, and that the information in it has not been tampered with. In particular, such authentication may be required for certificates of various kinds.
As an example, in the UK it is a requirement that any road vehicle over three years old should have a test certificate, referred to as an MOT certificate. These certificates are issued by licensed vehicle testing stations, following an inspection of the vehicle to check its roadworthiness and compliance with legal requirements. The certificate must be presented at a post office when the owner of the vehicle re-licenses it. Clearly, the post office should check that the certificate is not a forgery, and that the information in it has not been altered. At present, the post office clerk does this simply by making a visual check.
The object of the invention is to provide an improved method for authenticating printed documents.